Process for degumming vegetable textile fibers



United States Patent Office 2,700,608 Patented Jan. 25, 1955 PROCESS FOR DEGUMMING VEGETABLE TEXTILE FIBERS No Drawing. Application December 21, 1951, Serial No. 262,908

Claims priority, application France December 27, 1950 4 Claims. (Cl. 92-'-10) The present invention relates to a process for degumming vegetable textile fibres such as are obtained after chemical retting of lengths of vegetable textiles. By lengths of vegetable textiles are meant the vegetable textile materials (ramie, flax, hemp, urena, ambary, jute, etc.) the crude stalks of which have previously been sub jected to green soutching, that is to say to a treatment by which the greater part which the fibres are coated has been removed.

All the processes of chemical retting which are at present known have serious disadvantages. The fibres as obtained by the retting, although appearing to be well divided in the last rinsing Water, give on drying a gummed tow, that is to say a tow in which the fibres have become re-agglutinated and which it is consequently impossible to spin with a good output.

A process of de-gumming has long been sought, by which it is possible to obviate these difiiculties and to avoid gumming of the fibres. Numerous processes have been proposed but none of them appears to be 'satisfae tory in practice in order to obtain, during the spinning, a yarn of good nature and yield. 7

Consequently the de-gumming remains a serious problem in the textile industry.

, It is proposed in accordance with the present invention to provide a process of de-gumming which gives, after'an elfective chemical retting, i. e-., one Whichdoes not injure the cellulose both in the rinsing solutions and when dried and which consequently preserves the natural qualities of flexibility and softness to the touch of the fibre, while readily permitting spinning thereof.

The process according to the invention is based on the following considerations. After chemical retting, and notwithstanding the rinsing operations there remain on the surface of the fibres, forming a sheath-like coating thereon, pectic materials and hemicelluloses swelled by water in the state of a colloidal sol, which causes income plete degradation of the incrusting substances due to the retting. The successive rinsings with water are ineffective in removing this coating by reason of the high viscosity of the colloidal sol and the in'solubility of the hemicelluloses in Water.

Therefore, although the fibres appear to be highly divided in the rinsing solutions, the sol by which they are coated re-agglomerates on drying and sticks the fibres together again, whereby the gumming phenomenon is produced.

It must therefore be possible to remove these colloidal substances by rinsing in order to avoid gumming and this can only be done by permitting the rinsing water to penetrate between the colloidal particles so as to be able to entrain them instead of sliding thereon.

The interface tension between the solvent phase, i. e. the rinsing water, and the colloidal phase formed of pectic substances and hemicelluloses agglomerating on drying plays a great part in this phenomenon since, according to whether its value is higher on the surface of the sol or penetrates it intimately. This principle forms the basis of the process according to the invention, which concerns the de-gumming of vegetable textile fibres (ramie, fiax, hemp, urena, ambary, jute or the like), such as are obtained after chemical retting of vegetable fibres which are still coated with a of the ligneous substance by of the fibres, which is well divided i or lower, the water trickles sheath of pectic substances and hemicelluloses in the form of colloids which produce the gumming of the fibres. The said process is distinguished in particular by the fact that it consists in subjecting the said fibres to a first treatment with water containing a surface-active agent with active ions so as to reduce the face tension between the aqueous phase and the colloidal phase, then to a second treatment by an aqueous solution .of acid so as to fiocculate and precipitate the said colloids, and finally in subjecting the fibres to a rinsing with water.

The result is thus obtained that, owing to the action of the surface-active agent with active ions employed in the first treatment, the chemical agent employed in the second treatment can reach the very interior of the colloidal substance by which the fibres are coated and exert the maximum action on all the micellae of the colloids, and thus flocculate and precipitate them.

Surface-active substances suitable for the first treatment include any agents with active ions and endowed with surface activity, and it is thus possible to employ sulphated oils (copra oil, castor oil, linseed oil or the like), the sulpho-ricinoleates, the sulphonated fatty acids, whether esterified or not by alcohols, sulphonated fatty alcohol, aryl-alkyl-sulphonates, the hydroxy ethyl-amides of palm nut oil, sulphonated lauryl alcohol or the like.

The concentration of the surface-active substance may vary between 0.001% and 1% and his preferably in the neighborhood of 0.5%.

The acid employed for the second treatment performs, in fact, a double function in that, as an electrolyte it flocculates the colloid and, as an acid, it precipitates the constituents of the colloid, more especially the pectic substances.

Any mineral or organic acid is suitable for this second treatment. Thus, it is possible to employ sulphuric acid, hydrochloric acid, acetic acid, or the like. The concentration of the acid may vary between 0.2% and 2% and it is weaker in proportion as the dissociation constant of the acid is higher. Thus, for sulphuric acid, a concentration in the neighborhood of 0.2% will be satisfactory, while for acetic acid it is preferable to employ stronger concentrations, preferably of the order 0.5% to 1%.

I The process according to the invention is carried out in a simple manner by immersing the fibres in baths containing the aforesaid active constituents.

The treatment may be effected in two successive baths, the first containing the surface-active agent and the second containing the acid, in which baths the fibres are successively immersed without intermediate rinsing, or in a single bath containing both the acid and the surfaceactive agent if it is relatively stable in acid medium.

In each of the methods of carrying out the process, the temperature of the bath or baths is the ambient temperature and the duration of the passage through each bath or through the single bath varies between about 5 and 30 minutes.

After this treatment, the fibres are rinsed by washing and dried by the usual methods and do not re-agglomerate on drying. Flexible fibres are thus obtained which are sofltdto the touch and can readily be spun with a good yie The following examples, which are in no way limitative will enable the manner in which the invention can be carried into effect to be more readily understood.

Example 1 Fibres of retted flax are de-gummed by passing them successively through two baths of the following composition, the percentages being calculated on the weight of water in the bath.

1st bath: Water.

* Products of condensation of oleic acid with the sodium salts of isothionic acid.

The fibres are then rinsed with water and do not re-agglomerate when dry.

Example 2 The fibres of retted flax can be treated in a single bath of the following composition, the surface-active agent employed, i. e. sulphoricinoleic acid, being stable in acid medium.

Water.

dried aha Sulphoricinoleic acid per cent 0. Sulphuric acid do 0.2 Temperature C 15 Period of treatment min It is to be noted that the sulphuric acid is employed in a lower concentration than the acetic acid employed in Example 1, its dissociation constant being much higher. After having passed through this bath, the fibres are washed and dried.

Example 3 Fibres of retted ramie are de-gummed by treatment in a single bath of the following composition:

Water.

Hydrochloric acid per cent 0.5

Lauryl sulphuric acid do 0.3

Temperature C..- 20

Period of treatment min 20 The fibres are then washed and dried.

Example 4 lt-Libres of retted jute are treated in the following single ba Water.

Sulphuric acid "per cent 0.3

Ethyl-pyridinium bromide do.. 0.1

Temperature C 20 Period of treatment min The fibres are then washed and dried.

simultaneous action of an aqueous solution containing 0.001% to 1.0% of a wetting agent selected from the group consisting of sulphoricinoleic acid, lauryl sulphuric acid and ethyl-pyridinium bromide and an acid solution containing 0.2% to 2.0% of an acid selected from the group consisting of sulphuric acid and hydrochloric acid, and in which said wetting agent is stable, and then rinsing and drying said fibres.

2. A process for degumming vegetable textile fibres to make the latter suitable for spinning and weaving after they have been subjected to chemical retting; comprising the steps of subjecting the fibres, for a period of 10 minutes and at a temperature of 15 C., to the simultaneous action of an aqueous solution containing 0.5% of sulphoricinoleic acid and an acid solution containing 252% of sulphuric acid, and then rinsing and drying said res.

3. A process for degumming vegetable textile fibres to make the latter suitable for spinning and weaving after they have been subjected to chemical retting; comprising the steps of subjecting the fibres, for a period of 20 minutes and at a temperature of 20 C., to the simultaneous action of an aqueous solution containing 0.3% of lauryl sulphuric acid and an acid solution containing 0.5% of hydrochloric acid, and then rinsing and drying said fibres.

4. A process for degumming vegetable textile fibres to make the latter suitable for spinning and weaving after they have been subjected to chemical retting; comprising the steps of subjecting the fibres, for a period of 15 minutes and at a temperature of 20 C., to the simultaneous action of an aqueous solution containing 0.1% of ethylpyridinium bromide and an acid solution containing g% of sulphuric acid, and then rinsing and drying said res.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PROCESS FOR DEGUMMING VEGETABLE TEXTILE FIBRES TO MAKE THE LATTER SUITABLE FOR SPINNING AND WEAVING AFTER THEY HAVE BEENY SUBJECTED TO CHEMICAL RETTING; COMPRISING THE STEPS OF SUBJECTING THE FIBERS, FOR A PERIOD OF 5 TO 30 MINUTES AND AT A TEMPERATURE OF 5* C. TO 25* C., TO THE SIMULTANEOUS ACTION OF AN AQUEOUS SOLUTION CONTAINING 0.001% TO 1.0% OF A WETTING AGENT SELECTED FROM THE GROUP CONSISTING OF SULPHORICINOLEIC ACID, LAURYL SULPHURIC ACID AND ETHYL-PYRIDINIUM BROMIDE AND AN ACID SOLUTION CONTAINING 0.2% TO 2.0% OF AN ACID SELECTE FROM THE GROUP CONSISTING OF SULPHURIC ACID AND HYDROCHLORIC ACID, AND IN WHICH SAID WETTING AGENT IS STABLE, AND THEN RINSING AND DRYING SAID FIBRES. 